Country Lore: Avoid Flat Lawn Mower Tires

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I grew tired of having to air up the tires on my riding mower each time I used it. I tried “Slime” tire sealant, but with all the holes they had in them, the tires still went flat.

Then I had a hairbrained idea: inject all four lawn mower tires with foam. It worked great.

Here’s how to do it:

  1. Purchase at least two cans of minimal expanding rigid foam.
  2. Jack up the mower.
  3. Drill a hole just large enough for the canned foam’s spray tube. I turned the tire/wheel assembly so the valve stem was at the top, and then drilled the hole in the center tread of the tire itself. I removed the valve stem insert as well.
  4. Insert the tube into the tire and spray the foam into the tire. Watch for foam to start exiting the valve stem area; the foam will just have about filled the tire by that time. This also allows any air in the tire to exit. Replace the valve stem insert and cap to keep the foam from exiting.
  5. Keep filling the tire. Do this until the foam starts to exit the hole you drilled.
  6. Allow the foam-filled tire to remain jacked up for a few days to make sure the foam has cured.

After a couple of uses, the tire softened up some and started to get a flat spot when it sat for a few days. To remedy that, I added more foam.

Even if I have to do this a few times, eventually I think the foam will be compressed to a certain point where it will not compress anymore.

If you don’t want to do all this, there are tire shops that will fill tires for you.

Michael Barkley
Calera, Oklahoma

Here’s more information regarding foam-filled tires from Ken Burner’s Small Tractor FAQ website. — MOTHER EARTH NEWS

Urethane foam can be substituted for air in a tractor tire. Foam is available in several densities which approximate different inflation pressures. This is popular with construction equipment, but useful for small tractors as well. It is expensive: $40 or more for a small tire. Foam-filled tires are several times heavier than air-filled tires. Foam-filled tires are harder on a tractor’s steering mechanism than air-filled tires, since there is less “give” to the foam. Finally, foam filling does not make a thin tire stronger; in fact, it may put more stress on a tire than it was designed to withstand — resulting in a shredded tire with nothing to support the foam. So, this process is recommended only for heavy-duty tires. Most industrial tire dealers provide this service.”

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